Dual zone completion system

ABSTRACT

An arrangement is disclosed which makes it possible to (1) produce both zones of a dual completion well simultaneously or (2) permit either one of the two flowlines used in such production operation to be used as a service line for the other of said flowlines. In the disclosed arrangement, a tubing string is concentrically disposed within each of the production strings extending into the well. Valves selectively operable by means of a single control line are associated with the strings to alter the fluid flow path with respect to the strings and the flowlines to permit through-the-flowline operations to be carried out separately with respect to each zone or, alternatively, to allow production from both zones without commingling of the production fluid.

United States Patent De Vries [451 Aug. 22, 1972 [54] DUAL ZONECOMPLETION SYSTEM [21] Appl. No.: 747,903

[52] US. Cl ..l66/.5, 166/313 [51] Int. Cl. ..E2lb 43/01 [58] Field ofSearch ..166/.5, .6, 313, 315, 153, 166/154, 155,156

[56] References Cited UNITED STATES PATENTS 2,230,830 2/1941 Coberly..166/153 X 2,805,718 9/1957 Tausch ..166/313 X 3,136,363 6/1964 Yetmanet al. ..166/95 X 3,302,721 2/ l 967 Yetman ..166/313 3,363,693 l/l968Bohlmann ..166/313 3,394,760 7/1968 Childers et a1 ..166/315 3,444,9275/1969 Childers et a1 ..166/.5 3,454,084 7/ 1969 Sizer ..166/.6

3,101,118 8/1963 Culver ..166/.5

Primary ExaminerMarvin A. Champion Assistant ExaminerRichard E. FavreauAttorney-John H. McCarthy and Thomas R. Lampe [57] ABS I'RACT Anarrangement is disclosed which makes it possible to (1) produce bothzones of a dual completion well simultaneously or (2) permit either oneof the two flowlines used in such production operation to be used as aservice line for the other of said flowlines. 1n the disclosedarrangement, a tubing string is concentrically disposed within each ofthe production strings extending into the well. Valves selectivelyoperable by means of a single control line are associated with thestrings to alter the fluid flow path with respect to the strings and theflowlines to permit through-theflowline operations to be carried outseparately with respect to each zone or, alternatively, to allowproduction from both zones without commingling of the production fluid.

8 Clains, 6 Drawing Figures TO suPPLY ""SOURCE Patented Aug.,22, 19723,685,580

3 Sheets-Sheet 1 [TO SUPPLY souRcE INVENTOR:

D. DE VRIES /MOW HIS ATTORNEY Patented Aug. 22, 1912 3,685,580

' s Sheets-Sheet 2,

UPPER ZONE A FIG.3

' INVENTOR D. DE VRIES BY:

ms ATTORNEY LOWER ZONE B FIG. 2

Patented Aug.v 22, 1972 3 Sheets-Sheet 5 FIG. 5

I 24 LL, T0 SUPPLY I SOURCE INVENTOR:

D. DE VRIES HIS ATTORNEY DUAL ZONE COMPLETION SYSTEM This inventionrelates to the completion of wells having two spaced-apart distinctproducing zones or formations and pertains more particularly to anarrangement making it possible to (I) produce both zones simultaneouslywithout commingling the production and (2) permit either one of twoflowlines provided in such production operation to be used as a serviceline for the other of said flowlines.

This invention is especially adapted for use in carrying outthrough-the-flowline operations with respect to underwater wells.Through-the-flowline operations refer to techniques wherein various wellactivities, such as workover and maintenance operations, are carried outby tools which pass through a flowline extending between some remotelocation, such as an onshore storage facility, and the underwater wellinstallation. Such tools are normally moved within the flowline bypumping a driving fluid through the line. Operations representative ofthose which may be carried out through the use of such speciallydesigned through-theflowline tools are the opening of a packer, theremoval or insertion of a choke or valve, the cleaning of paraffin froma tubing string, etc. After being pumped through the flowline from theremote location, which is often a mile or more from the well, the toolenters the well and passes down the production tubing string, therein tobe subsequently positioned to perform the desired operation. Aftercompleting the operation, the tool is subsequently removed from the welland returned to the remote location, generally by reverse circulation ofdriving fluid through the flowline.

Through-the-flowline operations become more difficult in thosesituations wherein the tubing strings, through which the flowline toolsmust pass, extend into two fluid-producing zones rather than a singleproducing zone. Since the quality of the fluid produced in one zone maydiffer greatly from that produced in the other, it is desirable to keepthe fluids from the two zones separate. In addition, some states haveregulations which forbid the commingling of fluids from separateproducing zones.

While dual completion systems permitting throughthe-flowline workwithout commingling of fluids from the two zones have been devised inthe past, such systems are characterized by the fact that they are oftencomplex and expensive. In addition, such prior art systems routinelyrequire lengthy well down times to actuate the required controlarrangements associated therewith.

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to provide an improved dual completion system wherein twoproduction zones may be produced simultaneously without commingling theproduction fluids therefrom, and wherein either one of two flowlinesutilized in such production may be selectively used as a service linefor through-the-flowline operations with respect to the other of saidflowlines upon actuation of a suitable valving arrangement.

This and other objects have been attained in the present invention byproviding a dual zone completion system including a production stringextending into each zone. A tubing string is concentrically disposedwithin each production string to define an annular space therebetween. Avalve arrangement comprising a plurality of valves, all of which areselectively operable by means of a single control line, allow a fluidflow path to be established between the production flowline associatedwith one zone and the annular space and production string associatedwith the other zone whereby through-the-flowline operations may becarried out with respect to said other zone. Alternatively, the valvesmay be positioned to permit production from both zones.

Other objects, purposes, and characteristic features of the presentinvention will be obvious from the accompanying drawings and from thefollowing description of the invention.

DESCRIPTION OF THE DRAWING In describing the invention in detail,reference will be made to the accompanying drawings in which likereference characters designate corresponding parts throughout theseveral views, and in which:

FIG. 1 is a schematic view in partial longitudinal section illustratinga wellhead assembly positioned on the ocean floor;

FIG. 2 is a diagrammatic view taken in longitudinal cross-sectionillustrating elements of the dual completion system according to thepresent invention in operative association with a production casingstring and wellhead assembly;

FIG. 3 is a plan view in reduced scale of one element of the dualcompletion system shown in FIG. 2; and

FIGS. 4, 5 and 6 are schematic presentations illustrating fluid flowdirections in response to the setting or placement of the valvestructures associated with the present invention.

Referring to FIG. 1 of the drawings, a wellhead as sembly is shown aspositioned below the surface 11 of a body of water and preferably on theearth l2 underlying said body of water. The wellhead apparatus comprisesa platform 13 secured to the top of a conductor pipe or surface casing14 which in turn extends into the earth l2 and is preferably cementedtherein in a conventional manner. The wellhead assembly may also beprovided with two or more vertically-positioned guide columns 15 and 16which are fixedly secured at their lower ends to the platform 13. A wellcasing head 17 is mounted on the top of conductor pipe 14 with a controlequipment housing 18 closing the top of the casinghead and/or any casingand tubing suspension equipment employed on the wellhead assembly, aswell as the various control valves and other equipment normally used onthe top of a well of this type.

Emerging from the housing 18 are two flowlines l9 and 20 whichpreferably bend in long sweeping curves from a vertical position down toa substantially horizontal position so that they can run along the oceanfloor 12 to a remote location where fluid from the well, and normallyfrom other wells, is collected and metered and treated. Such acollection station may be several miles away from the various wellsassociated therewith. The well may be provided with one or more stringsof well casing 21 suspended within the conductor pipe 14. The flowlinesl9 and 20, respectively, are in fluid communication with two productionstrings 22 and 23 which depend within the well in the mannerillustrated. Also emerging from housing 18 and extending toa suitablepower source (not shown) is a hydraulic line 24, the purpose of whichwill be more fully brought out below. I

I Referring now to FIG. 2, a cylindrical casing head member or casinghanger 25 having a bevelled lower portion or landing surface 26 isseated within well casing head 17. In such position, the bevelled lowerportion 26 of member 25 is in seating engagement with a cooperatinginwardly-extending shoulder member or landing surface 27 of casing head17 thereby preventing member 25 from moving downwardly with respect tocasing head 17. Casing string 21 is threadedly engaged or otherwisesecured to member 25 and extends into the well in the usual manner.Surface casing or conductor pipe 14 is welded or otherwise fixedlysecured to casing head 17, as shown. As previously stated, surfacecasing 14 is preferably cemented in the earth 12 below body ofwater 11(FIG. 1

A dual tubing hanger or manifold means 28 is seated within cylindricalcasing head member 25, as shown in FIG. 2,. with sloping wall 29 ofhanger 28 cooperating with inwardly projecting shoulder 30 of casinghead member 25 to maintain these elements in position.

Preferably, dual tubing hanger 28 is provided with an walls-thereof arein alignment with the walls of hanger 28 which define throughbores 33and 34. Production string 22 and 23depend within the well and terminateat their lower ends within an upper producing zone A and a lowerproducing zone B, respectively, within the well. At their lowermostends, production string 22 and 23 are shown as being cemented asat 35and 36 and provided with a series of perforations 37 and 37a through thetubing string walls and the cement. These perforations permit fluid fromthe production zones A and B to enter into the interior of theproduction strings. It should be noted at this juncture that the fluidzones A and B are segregated one from the other to avoid anycomminglin'g of the production fluid. Although not illustrated, one ormore packers may be utilized to accomplish this result in the well knownmanner. I

Positioned above dual tubing hanger 28 is a second tubing hanger ormanifold means 38 which includes two full-bore tubing runs 39 and 40. Aswith dual tubing hanger 28, hanger 38 includes a sloping wall 41 whichseats upon inwardly projecting shoulder 30 of casingheadmember 25 tosupport the hanger in position. Tubing run 39 is bored out, as at 42, toform a fullopening production seal sub in the form of a downwardlyextending nipple 43. Nipple 43 is fitted telescopically over and influid-tight engagement with an upstanding nipple 44 which is formed atthe top of dual tubing hanger 28. Suitable seals (not shown), which maybe in the form of O-ring seals, are provided between adjacent surfacesofnipples 43 and 44 to ensure fluid-tight engagement therebetween. Inaddition,

suitable seal means may be utilized to make certain that sloping wall 41of hanger '28 is in fluid-tight engagement with shoulder 30 as it issupported thereupon.

In addition to the two full-bore tubing'runs 39 and 40, tubing hanger 38includes circulating ports 45 and 46 having a somewhat smaller diameterthan the diameter of the tubing runs. FIG. 3 is a plan view in reducedscale of the top of hanger 38 as viewed in FIG. 2. As may be seenclearly with reference to FIGS. 2 and 3, port 45 exists'from the top ofhanger 38with the 7 center line thereof in alignment with the centerlines of tubing runs 39 and 40 while port 46 emerges from the top of thehanger 38 in ofl'set relation thereto. With particular reference to FIG.2, it may be seen that circulating port 45 passes through hanger 38 andconnects with bore 42 within nipple or seal sub 43 while circulatingport 46 is bored within hanger 38 to exit from the space 46a below thetubing hanger 38 outside seal sub being formed between the inner wall ofproduction string 23 and the outer wall of tubing string 51.

Tubing string 50. and 51 extend downwardly along substantially the fulllengths of their associated production string and terminate at theirdepending ends just above perforations 37 formed in the productionstring. The tubing string are open at the bottom and house conventionalstanding valves within their terminal portions. In this instance thevalves include ball valve members 54 and '55 which cooperate withperipheral sloping shoulders 54a and 55a at the ends of the tubingstring to allow upward passage of fluid into the tubing string throughthe apertures defined by the sloping shoulders but prevent downward,passage of fluid therethrough. Inwardly projecting pins 546 and 55bdetermine the limits of the upward path of movement of the ball valvemembers. Packers 56 and 57 are provided to close off annular spaces 52and 53 in the vicinity of the standing valve members and circulationports 58 and 59 are formed in the tubing string above the packers. Inthis way, free fluidcommunication may be established between the annularspaces 52 and 53 and the respective interiors of tubing string 50 and51.

Although production string 22 and 23 terminate at their uppermost endsby being threadedly engaged to dual tubing hanger 28, annular spaces 52and 53 continue upwardly through that hanger and are defined at thispoint by the outer walls of tubing string 50 and 51 and the walls ofhanger 28 defining throughbores 33 and 34. Above dual tubing hanger 28,annular spaces 52 and 53 communicate, respectively, with bore 42 andspace 46a. 7

A production tree 60, illustrated in A schematic fashion, is positionedabove well casing head 17 and attached thereto by means of treeconnector 61, also illustrated somewhat schematically, as by means oflock ring 62 of any suitable construction. The body of the productionwellhead assembly of tree 60 is provided with a pair of verticalconduits 63 and 64 which terminate in two downwardly-extending sealnipples or subs 65 and 66. It may be assumed that conduits 63 and 64communicate respectively with production flowlines 19 and 20 (FIG. 1).Seal nipples 65 and 66 extend into cooperating recesses in the upperportion of tubing hanger 38 as shown in FIG. 2 so that the throughboreof conduit 63 is in communication with the interior of tubing string 50and the throughbore of conduit 64 is in communication with the interiorof tubing string 51. Preferably seals, such as O-ring seal 67, areprovided to ensure fluid-tight engagement between the subs or nipples 65and 66 and the cooperating recesses of hanger 38.

The lower end of the production tree also carries two circulating portseal subs 68 and 69 which fit into additional cooperating recesses atthe top of hanger 38 and communicate, respectively, with circulatingports 45 and 46 which pass through the hanger as previously described.At its upper end seal sub 68 branches out into a bypass conduit 70 whichpasses through the tree body and thence in looping fashion intocommunication with the throughbore of conduit 64 above a gate valve 71which is disposed in said throughbore. Similarly, seal sub 69 cooperateswith a bypass conduit 72 which is in fluid communication with thethroughbore of conduit 63 above a gate valve 73 which is disposed inthat throughbore.

Each bypass conduit is also provided with a valve of any desired typesuch as schematically illustrated gate valves 74 and 75. Valves 71, 73,74 and 75 are preferably hydraulically actuated with one hydraulicactuator unit being operatively associated with both a throughbore gatevalve and the valve disposed in the bypass conduit cooperating with thatthroughbore. Accordingly, hydraulic actuator unit 76 is operativelyassociated with valves 73 and 74 and hydraulic actuator unit 77 isoperatively associated with valves 71 and 75. In addition to theaforementioned valves, hydraulically actuated master valves 78 and 79having actuators 78a and 79a, respectively, may also be disposed in thechristmas tree throughbore.

The operation of the previously described arrangement will now bedescribed in detail. With particular reference to both FIGS. 2 and 4,the operation of the present invention will be set forth for thesituation in which upper zone A is shut in and the flowline associatedtherewith is used as a service line for throughthe-flowline (TFL) workwith respect to zone B. FIG. 4 shows the position assumed by the variousvalve members associated with the present invention for this operation.It should be noted at this point that one hydraulic control line may beused with the present system to provide for all operating conditions. Inthe first operating condition, i.e. that permitting TFL work withrespect to zone B, both master valves 78 and 79 are open to permit freefluid flow through their respective vertical throughbores of conduits 63and 64. Gate valve 73 in the lower portion of the throughbore of conduit63 is, however, closed under control of the hydraulic actuation unit 76while gate valve 74 in bypass conduit 72 is open, also under theinfluence of actuator unit 76. Hydraulic actuator unit 77, on the otherhand, maintains gate valve 71 disposed within the throughbore of conduit64 in an open condition, thus permitting free fluid flow through theentire length of that throughbore. Valve 75 within bypass conduit ismaintained in a closed position by actuator 77.

With the valves in the above-described first operating condition, afluid circuit is established whereby fluid may be pumped throughproduction flowline 19 (FIG. 1) into conduit 63. Since gate valve 73 isclosed, the flow of production fluid from upper zone A is halted and thefluid pumped down conduit 63 passes through bypass conduit 72, throughseal sub 69 and thence into circulating port 46 within hanger 38. Thepumped fluid exits from hanger 38 into space 46a and flows downwardlyinto annular space 53 formed between the inner wall of production string23 and the outer wall of tubing string 51. After passing throughcirculation ports 59, the pumped fluid passes up tubing string 51 sinceit is prevented from exiting from the bottom thereof by ball valvemember 55. Finally, the fluid passes up and through conduit 64 (throughopen valve 71) and out production flowline 20.

The just-described fluid flow circuit is illustrated in schematicfashion in FIG. 4. It is obvious that the path of fluid flow through thevalves positioned as illustrated in that Figure may be reversed simplyby introducing the pumped fluid into flowline 20 rather than throughflowline 19. In this manner through-the-flowline tools may be introducedinto tubing string 51 and removed therefrom as desired without lengthywell down times caused by complicated operations with respect to theoften complex prior art systems.

The construction of the hydraulic actuator units employed for valveplacement may be seen with particular reference to actuator unit 77 inFIG. 4. In essence, the unit includes a cylindrical housing 80 in whicha piston 81 is positioned for relative movement with respect thereto. Inthe form shown, the piston is continuously urged to the left by acompression string 82. Valves and 71 are both connected by suitablearmature members to piston 81 and are thus maintained in the positionillustrated in FIG. 4 under the influence of spring 82. In like manner,hydraulic actuator unit 76 functions to normally maintain valves 73 and74 in the respective positions illustrated in FIG. 4. The correspondinglocation of piston 83 within the housing of actuator unit 76 isillustrated by means of hidden lines. Hydraulic actuator units 76 and 77are connected by means of suitable conduit means to hydraulic line 24 asshown so that the interiors of the actuator housings are in fluidcommunication therewith on the sides of pistons 81 and 83 opposed to therespective compression springs.

By introducing pressurized hydraulic fluid of suflicient value fromhydraulic line 24 into the interiors of the actuator housings, pistons81 and 83 will be caused to move against their respective compressionsprings in an obvious manner. The springs are of differing strengths sothat, for example, piston 83 (and consequently valves 73 and 74) willmove to the right at a hydraulic pressure of 500 psi while piston 81 andits associated valves will move against the applied spring load at ahydraulic pressure of somewhat greater value, e.g., 1,500 psi. When theabove-described first operating condition exists, however, no hydraulicpressure is introduced through line 24 and both sets of valves are urgedto the left (as viewed in FIG. 4) by the compresslon springs.

By introducing 500 psi of pressurized hydraulic fluid into the systemthrough line 24, piston 83 moves to the right against its associatedcompression spring as shown in FIG. 5, which illustrates in schematicfashion the positions assumed by the various valves-in the secondoperating condition assumedby the elements of the present invention. Inthis condition, valve 71' remains open and valve 75 remains closed sincethe pressure of the hydraulic fluid introduced through line 24 isinsufi'icient to urge piston 81 to the right against the urging of itsassociated spring. However, since piston 83 has moved to the right,valve 73 is opened and valve 74 is closed. With the valves in thissecond operating condition, bypass conduits 70 and 72 are closed andafluid circuit is established whereby full fluid communication existsbetween the full lengths of the throughbores of conduits 63 and 64 andthe interiors of tubing strings 50 and 51, respectively. Productionfluid thus flows from both upper zone A and lower zone B throughproduction flowlines l9 and 20, respectively, to the storage facility(not shown). This fluid is illustrated schematically in FIG. by thearrows.

By increasing the hydraulic operating pressure through line 24 to 1,500psi or above, piston 81 and the associated valves 71 and 75 move to thepositions shown in FIG. 6. The system is now in thethird, and final,operating condition. With the valves 71, 73, 74 and 75 in the conditionillustrated, lower zone B is shut in with the production from that zonetemporarily terminated. A fluid circuit is established whereby flowlinemay be used to pump fluid into annulus 52 and out flowline 19 in muchthe same manner as that previously described with respect to TFL work inzone B (the first operating condition).

While this invention has been described with particular reference to apreferred embodiment thereof, it should be understood that theparticular form disclosed has been selected to facilitate explanation ofthe invention rather than to limit the number of forms which it mayassume. Further, it should be understood that various modifications,alterations, and adaptations may be applied to the specific formsdescribed to meet the requirements of practice without in any mannerdeparting from the spirit of the invention or the scope of the subjoinedclaims.

I claim as my invention:

1. Apparatus for use with a well having an upper producing zone and alower producing zone, said apparatus comprising:

a first tubing string extending downwardly from the top of the well intosaid upper zone, at least a portion of said first tubing string beingdisposed within the interior of a first production string which extendsinto said upper producing zone;

a second tubing string extending downwardly from the top of the wellinto said lower zone, at least a portion of said second tubing stringbeing disposed within the interior of a second production string whichextends into said lower producing zone;

means including hanger means for supporting said production stringsandsaid tubing strings in substantially fixed relationship to one anotherwhereby a first annular space is formed between said first productionstring and said first tubing string and a second annular space is formedbetween said second production string and said second tubing string,

flowline means including a first production flowline and a secondproduction flowline extending outwardly from said well;

valve means operatively associated with said tubing strings and saidflowline means to. selectively establish fluid communicationtherebetween;

actuating means associated with said valve means whereby operation ofsaid actuating means causes said valve means to selectively assume threedistinct operating conditions;

said valve means in its first operating condition establishing a fluidflow circuit between said first production flowline, said second tubingstring, said second annular space and said second production flowlinewhereby-through-the-flowline operations may be carried out with respectto said lower producing zone;

said valve means in its second operating condition establishing a fluidflow circuit between said first production flowline and said firsttubing string and between said'second production flowline ans saidsecond tubing string whereby production fluid may be produced from bothsaid upper zone and said lower zone without commingling of saidproductionfluid; and

said valve means in its third establishing a fluid flow circuit betweensaid first production flowline, said'first tubing string, said firstannular space and said second'production flowline wherebythrough-the-flowline operations degree of pressure of the fluid in saidline.

3. The apparatus according to claim 1 wherein a production well-headassembly is disposed above said hanger means, said wellhead assemblyincluding conduit means disposed between said flowline means and saidtubing strings and in operative association therewith;

bypass means branching off from said conduit means and in fluidcommunication with said first and second annular spaces; and

said valve means being operativelyassociated with said conduit means andwith said bypass means to interrupt fluid communication between saidfirst production flowline and said first tubing string when said valvemeans is in said first operating condition and to interrupt fluidcommunication between said second production flowline and said secondtubing string whensaid valve means isin said third operating condition.

4. The apparatus according to claim 3 wherein said wellhead assemblyconduit means includes a first throughbore and a second throughborepassing through said wellhead assembly in spaced relationship to oneanother;

said bypass means comprising a first bypass conduit and a second bypassconduit, said first bypass conduit branching off from said firstthroughbore and said second bypass conduit branching off from saidsecond throughbore, said first bypass conduit being in fluidcommunication with said second anoperating condition I nular space andsaid second bypass conduit being in fluid communication with said firstannular space; and

said valve means when in said second and third operating conditionsinterrupting fluid flow within said first bypass conduit and said valvemeans when in said first and second operating conditions interruptingfluid flow within said second bypass conduit.

5. The apparatus according to claim 2 wherein said hanger means includescirculating port means through which fluid flow communication isestablished between said bypass means and said annular spaces.

6. In combination:

first and second tubing strings extending into a well;

first and second production strings extending into said well andrespectively disposed in concentric spaced relationship with respect tosaid first and second tubing strings; first valve means and second valvemeans, said valve means being operatively associated with said tubingstrings and with said production strings to modify the path of fluidflow therethrough; and

actuating means associated with said valve means whereby operation ofsaid actuating means causes said valve means to move to one of aplurality of selected positions to condition said tubing strings andsaid production strings for either production of fluid from said well orthrough-the-flowline operations.

7. The combination according to claim 6 wherein said actuating meanscomprises a plurality of actuator units operatively associated with andcontrolled by a single control line.

8. In combination:

first and second tubing strings extending into a well;

first and second production strings extending into said well andrespectively concentrically disposed in spaced relationship with respectto said first and second tubing strings;

manifold means positioned at the upper ends of said tubing strings andsaid production strings, said manifold means defining fluid flow passagemeans in communication with respective interiors of said tubing stringsand said production strings;

flowline means extending from said manifold means and in fluidcommunication with said fluid flow passage means;

bypass means operatively associated with and in fluid communication withsaid flowline means and said manifold fluid flow passage means;

valve means associated with said flowline means and said bypass means,said valve means being selectively movable to one of a plurality ofpreselected positions to permit through-the-flowline operations to becarried out with respect to the well through said flowline means or thepassage of production fluid from said well through said flowline means;and

actuator means to position said valve means.

1. Apparatus for use with a well having an upper producing zone and alower producing zone, said apparatus comprising: a first tubing stringextending downwardly from the top of the well into said upper zone, atleast a portion of said first tubing string being disposed within theinterior of a first production string which extends into said upperproducing zone; a second tubing string extending downwardly from the topof the well into said lower zone, at least a portion of said secondtubing string being disposed within the interior of a second productionstring which extends into said lower producing zone; means includinghanger means for supporting said production strings and said tubingstrings in substantially fixed relationship to one another whereby afirst annular space is formed between said first production string andsaid first tubing string and a second annular space is formed betweensaid second production string and said second tubing string, flowlinemeans including a first production flowline and a second productionflowline extending outwardly from said well; valve means operativelyassociated with said tubing strings and said flowline means toselectively establish fluid communication therebetween; actuating meansassociated with said valve means whereby operation of said actuatingmeans causes said valve means to selectively assume three distinctoperating conditions; said valve means in its first operating conditionestablishing a fluid flow circuit between said first productionflowline, said second tubing string, said second annular space and saidsecond production flowline whereby through-the-flowline operations maybe carried out with respect to said lower producing zone; said valvemeans in its second operating condition establishing a fluid flowcircuit between said first production flowline and said first tubingstring and between said second production flowline and said secondtubing string whereby production fluid may be produced from both saidupper zone and said lower zone without commingling of said productionfluid; and said valve means in its third operating conditionestablishing a fluid flow circuit between said first productionflowline, said first tubing string, said first annular space and saidsecond production flowline whereby through-the-flowline operations maybe carried out with respect to said upper producing zone.
 2. Theapparatus according to claim 1 wherein said actuating means isoperatively associated with a single hydraulic control line with theoperating condition assumed by said valve means being responsive to thedegree of pressure of the fluid in said line.
 3. The apparatus accordingto claim 1 wherein a production well-head assembly is disposed abovesaid hanger means, said wellhead assembly including conduit meansdisposed between said flowline means and said tubing strings and inoperative association therewith; bypass means branching off from saidconduit means and in fluid communication with said first and secondannular spaces; and said valve means being operatively associated withsaid conduit means and with said bypass means to interrupt fluidcommunication between said first production flowline and said firsttubing string when said valve means is in said first operating conditionand to interrupt fluid communication between said second productionflowline and said second tubing string when said valve means is in saidthird operating condition.
 4. The apparatus according to claim 3 whereinsaid wellhead assembly conduit means includes a first throughbore and asecond throughbore passing through said wellhead assembly in spacedrelationship to one another; said bypass means comprising a first bypassconduit and a second bypass conduit, said first bypass conduit branchingoff from said first throughbore and said second bypass conduit brancHingoff from said second throughbore, said first bypass conduit being influid communication with said second annular space and said secondbypass conduit being in fluid communication with said first annularspace; and said valve means when in said second and third operatingconditions interrupting fluid flow within said first bypass conduit andsaid valve means when in said first and second operating conditionsinterrupting fluid flow within said second bypass conduit.
 5. Theapparatus according to claim 2 wherein said hanger means includescirculating port means through which fluid flow communication isestablished between said bypass means and said annular spaces.
 6. Incombination: first and second tubing strings extending into a well;first and second production strings extending into said well andrespectively disposed in concentric spaced relationship with respect tosaid first and second tubing strings; first valve means and second valvemeans, said valve means being operatively associated with said tubingstrings and with said production strings to modify the path of fluidflow therethrough; and actuating means associated with said valve meanswhereby operation of said actuating means causes said valve means tomove to one of a plurality of selected positions to condition saidtubing strings and said production strings for either production offluid from said well or through-the-flowline operations.
 7. Thecombination according to claim 6 wherein said actuating means comprisesa plurality of actuator units operatively associated with and controlledby a single control line.
 8. In combination: first and second tubingstrings extending into a well; first and second production stringsextending into said well and respectively concentrically disposed inspaced relationship with respect to said first and second tubingstrings; manifold means positioned at the upper ends of said tubingstrings and said production strings, said manifold means defining fluidflow passage means in communication with respective interiors of saidtubing strings and said production strings; flowline means extendingfrom said manifold means and in fluid communication with said fluid flowpassage means; bypass means operatively associated with and in fluidcommunication with said flowline means and said manifold fluid flowpassage means; valve means associated with said flowline means and saidbypass means, said valve means being selectively movable to one of aplurality of preselected positions to permit through-the-flowlineoperations to be carried out with respect to the well through saidflowline means or the passage of production fluid from said well throughsaid flowline means; and actuator means to position said valve means.